Coupling portion of a chain

ABSTRACT

A chain has pairs of inner sheets and pairs of outer sheets. Each sheet has two rings. An annular flange is formed on each ring. An inner surface of an opposite end to a free edge of each annular flange is rounded so as to form a recess. Each annular flange of the outer sheet is received in the recess of one inner sheet. A pin is inserted through the annular flanges of a pair of inner sheets and a pair of outer sheets. A head of the pin is received in the recess of the outer sheet. The other end of the pin is deformed so as to be received in the recess of the other outer sheet.

BACKGROUND OF THE INVENTION

The present invention relates to a chain, and more particularly to a coupling portion of a chain.

Chain is widely used as chain transmission in bicycle or motorcycle. A conventional chain is shown in FIGS. 4 and 5 and comprises a plurality pairs of inner sheets I and a plurality pairs of outer sheets O alternatively coupled together. A pair of bushes B are coupled between every pair of inner sheets I. A roller R is rotatably provided on each bush B. A pin P passes each bush B and is fixed between each pair of outer sheets O. Both ends of each pin P extend beyond the outer sheets O. The ends of the pin P are disc shaped so that the sheets I and O are coupled together. The protruded ends of the pins P affect the shifting of the gears of the bicycle which has multispeeds.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional chains.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a coupling portion of a chain which has a flat outer surface without protrusions.

In accordance with one aspect of the invention, there is provided a chain which includes a number of pairs of inner sheets and a number of pairs of outer sheets alternatively coupled together. Each inner sheet and outer sheet has two rings integrally formed together. An annular flange is formed on a center of each ring. An inner surface of an opposite end to a free edge of each annular flange is rounded so as to form a recess. A roller is rotatably supported between each pair of annular flanges of the inner sheets. Each annular flange of the outer sheet is received in one recess. A pin is inserted through the annular flanges of a pair of inner sheets and a pair of outer sheets. The head of the pin is received in the recess of the outer sheet. The other end of the pin is deformed so as to be received in the recess of the other outer sheet.

Further objectives and advantages of the present invention will become apparent from a careful reading of the detailed description provided hereinbelow, with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a chain in accordance with the present invention;

FIG. 2 is a partial cross sectional view of the chain, in which an outer sheet is separated;

FIG. 3 is a partial cross sectional view of the coupling portion of the chain;

FIG. 4 is an exploded view of a conventional chain; and

FIG. 5 is a partial cross sectional view of the conventional chain.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and initially to FIGS. 1 and 2, illustrated is a section of a chain in accordance with the present invention. Each section comprises generally a pair of outer sheets 1 and a pair of inner sheets 2 which are alternatively coupled together to form the chain. Each sheet 1, 2 is substantially bone shaped or has substantially two rings 10, 20 integrally fixed together. Each ring 10, 20 has an annular flange 11, 21 which is substantially perpendicular to the ring 10, 20. The inner surface of the opposite end to the free edge of each annular flange 11, 21 is rounded so as to form a recess 12, 22. The outer peripheral surface of the annular flange 11 is tapered, or, the width of the annular flange 11 is reduced toward the free edge thereof so that the annular flange 11 is receivable in a respective recess 22 and so that the inner surfaces of the annular flanges 11, 21 are aligned. Two rollers 3 which are cylindrical are slidably supported between each pair of inner sheets 2 around the annular flanges 21 thereof. A pin 4 has a head 41 formed on one end and a depression 42 formed in the other end thereof. The outer diameter of the pin 4 is equal or slightly less than the inner diameter of the annular flanges 11, 21 so that the pin 4 is insertable into the annular flanges 11, 21. Alternatively, the pin 4 may be a cylindrical tube.

Referring next to FIG. 3, the pin 4 is inserted through the annular flanges 11, 21 of a pair of inner sheets 2 and a pair of outer sheets 1. The head 41 of the pin 4 is received and engaged in the recess 12 of an outer sheet 1. The opposite end of the pin 4 is pressed or deformed so that this end is enlarged and is engaged in the recess 12 of the other outer sheet 1. The ends of the pin 4 are substantially embedded in the outer sheets 1 so that the outer surfaces of the outer sheets 1 are flat and have no protrusions.

Accordingly, the coupling portion of the chain in accordance with the present invention has a flat outer surface without protrusions. The chain is particularly suitable for being used in the bicycles which have shifting gears for changing speeds.

Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the detailed construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed. 

I claim:
 1. A coupling portion of a chain, said chain comprising a plurality pairs of inner sheets and a plurality pairs of outer sheets alternatively coupled together; each said inner sheet having two first rings integrally formed together, a first annular flange being formed on a center of each said first ring and being substantially perpendicular to said inner sheet; each said outer sheet having two second rings integrally formed together, a second annular flange being formed on a center of each said second ring and being substantially perpendicular to said outer sheet, a width of each said second annular flange being gradually decreased toward a free edge thereof; an inner surface of an opposite end to a free edge of each said first annular flange being rounded so as to form a first recess, and an inner surface of an opposite end to said free edge of each said second annular flange being rounded so as to form a second recess; a pair of rollers being rotatably supported between each pair of said inner sheets around said first annular flanges of said inner sheets; each said second annular flange of said outer sheet being received and engaged in a respective first recess; a pin having a head formed on one end and a depression formed in an other end thereof, said pin being inserted through a pair of said first annular flanges and a respective pair of said second annular flanges which are aligned, said head of said pin being engaged and received in one of said second recesses, and said other end of said pin being deformed so as to be enlarged and engaged in a respective second recess; and both ends of said pin being substantially embedded in said outer sheets so that said outer sheets have a flat outer surface without protrusions. 